Polymer nano composite material with magnetoelectric effect and preparation method thereof

Abstract

The invention relates to the field of polymer nano composite materials, in particular to a polymer nano composite material with a magnetoelectric effect and a preparation method of the polymer nano composite material with the magnetoelectric effect, raw materials of the composite material comprise vanadium, selenium, carboxyl diazonium salt and polyvinylidene fluoride, and the orientation factor of the composite material is 0.55-0.71. Based on the total mass of polyvinylidene fluoride in the composite material, the content of the beta phase is 78-86%, and the composite material has good ferromagnetic performance, ferroelectric performance and mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of polymer nanocomposites, and more particularly to a polymer nanocomposite with magnetoelectric effect and its preparation method. Background Technology

[0002] Magnetoelectric materials are a class of functional materials that possess both ferromagnetic and ferroelectric properties, and these two properties can be coupled and converted between each other through external stimuli (such as magnetic and electric fields). Their core characteristic is the "magnetoelectric effect," i.e., the ability to bidirectionally convert between magnetic and electric fields. This is the key difference between them and materials with only ferromagnetic or ferroelectric properties. These unique physical properties endow magnetoelectric materials with enormous application potential in multiple fields such as information storage, sensors, energy harvesting, and energy conversion. However, traditional magnetoelectric materials often suffer from high hardness and brittleness, making it difficult to meet the requirements of flexible electronic devices. Polyvinylidene fluoride (PVDF), a typical ferroelectric polymer, possesses good flexibility and tunable ferroelectric properties. Its ferroelectric properties are mainly related to the content of its internal β-phase and it is often used to prepare magnetoelectric materials by combining it with other nanofillers possessing ferromagnetic properties.

[0003] However, when polyvinylidene fluoride (PVDF) is combined with other ferromagnetic nanofillers to prepare materials with magnetoelectric effects, the internal structure is usually disordered. Ferromagnetic nanofillers are mostly inorganic materials with inert surfaces (e.g., non-polar functional groups) and are prone to aggregation; while PVDF is a polar polymer. The significant difference in chemical properties between the two results in weak interfacial interactions, primarily van der Waals forces, lacking directional forces. Therefore, during the composite process, the nanofillers struggle to form ordered binding sites with the PVDF molecular chains. The molecular chains and nanoparticles tend to disperse randomly, leading to an overall disordered structure. This disordered structure makes it easier for the PVDF molecular chains to spontaneously form the nonpolar, lower-energy α phase, rather than the most polar β phase, resulting in a low β phase content. In other words, due to the disordered internal structure and the low β phase content in PVDF, the ferromagnetic, ferroelectric, and mechanical properties of the composite material require further improvement.

[0004] CN101286545A discloses a composite thin-film heterojunction with magnetoelectric effect and its preparation method. The composite thin-film heterojunction is formed by combining a material with piezoelectric effect and a material with magnetostrictive effect. The key features are: the material with magnetostrictive effect is a rare-earth iron alloy RFe2 nanofilm, where R is a rare-earth element; the material with piezoelectric effect is a flexible PVDF polymer piezoelectric film; the two films are combined by depositing the rare-earth iron alloy RFe2 nanofilm on the PVDF piezoelectric film to form an RFe2 / PVDF bilayer nanocomposite film. The preparation method of this RFe2 / PVDF bilayer nanocomposite film involves continuously depositing RFe2 clusters onto the surface of the PVDF piezoelectric film using a beam of electricity to form an RFe2 nanofilm layer. In this invention, the PVDF polymer film serves as both the piezoelectric functional layer and the substrate of the RFe2 nanofilm layer. Although RFe2 nanoparticles achieved monodispersion (without significant agglomeration) through directional beaming, their directional arrangement was not controlled. The particles randomly stacked to form a thin film layer with irregular orientation (the shapes of the in-plane and out-of-plane hysteresis lines are similar, indicating that anisotropy is not obvious). At the same time, the random distribution of RFe2 particles caused the PVDF molecular chains to be confined in disordered space, making it difficult to form a polar β phase. Instead, the PVDF exists more as a thermodynamically stable α phase. In other words, due to the disordered internal structure and the low content of the β phase in PVDF, the ferromagnetic properties, ferroelectric properties, and mechanical strength of this material need to be further improved.

[0005] CN110372977B discloses a ferromagnetic composite polymer nanofilm and its preparation method. The nanofilm uses CFO as a core, coated with insulating ferroelectric BT nanoparticles and a polydopamine PDA organic shell. This core-shell structure of CFO@BT@PDA nanoparticles serves as the inorganic dopant phase in a P(VDF-TrFE) polymer-based composite material. Although the core-shell CFO@BT@PDA particles are more uniformly dispersed after BT and PDA coating, they still lack directional arrangement and are randomly distributed in the matrix, exhibiting disordered dispersion. Furthermore, this random distribution leads to uneven local stress, causing molecular chains to easily coil into the α phase. Defects in the agglomeration regions (such as voids and stress concentrations) further inhibit the nucleation and stabilization of the β phase. Therefore, due to the disordered internal structure and the low β phase content in P(VDF-TrFE), the ferromagnetic properties, ferroelectric properties, and mechanical strength of this material require further improvement.

[0006] Therefore, how to simultaneously improve the ferromagnetic properties, ferroelectric properties, and mechanical strength of polyvinylidene fluoride nanocomposites is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a polymer nanocomposite material with magnetoelectric effect. The raw materials of the composite material include vanadium, selenium, carboxyl diazonium salt and polyvinylidene fluoride. The orientation factor of the composite material is 0.55-0.71. Based on the total mass of polyvinylidene fluoride in the composite material as a percentage, the content of β phase is 78-86%. This composite material has good ferromagnetic properties, ferroelectric properties and mechanical strength.

[0008] This invention provides a polymer nanocomposite material with magnetoelectric effect. The raw materials of the composite material include vanadium, selenium, carboxyl diazonium salt and polyvinylidene fluoride. The orientation factor of the composite material is 0.55-0.71, and the content of β phase is 78-86% based on the total mass of polyvinylidene fluoride in the composite material.

[0009] Furthermore, in the XRD diffraction pattern of the composite material: the (020) characteristic diffraction peak of the α phase of the polyvinylidene fluoride was observed at a 2θ angle of 18.6±0.2°, and the (110) characteristic diffraction peak of the β phase of the polyvinylidene fluoride was observed at a 2θ angle of 20.6±0.2°.

[0010] Furthermore, in the infrared spectrum of the composite material: at wavenumbers of 763±3 and 876±3 cm⁻¹ -1 The α-phase characteristic peaks of the polyvinylidene fluoride were observed at wavenumbers of 840±3, 1071±3, 1168±3, 1273±3, and 1403±3 cm⁻¹. -1 The β-phase characteristic peak of the polyvinylidene fluoride was observed at [location].

[0011] Furthermore, based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75-90%.

[0012] Furthermore, based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75%.

[0013] Furthermore, at 25°C, the saturation magnetization of the composite material is 0.4-8.3×10⁻⁶. -3 The composite material has an emu / g content, a Curie temperature of 130.3-156.9℃, and a fracture strength of 16.4-47.9MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0014] This invention provides a method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix vanadium and selenium, then add a transport agent to obtain a mixture. Seal and heat the mixture sequentially to obtain vanadium diselenide crystals. Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals in Step 1 are stripped, and then separated and washed sequentially to obtain vanadium diselenide nanosheet dispersion; Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add carboxyl diazonium salt to the vanadium diselenide nanosheet dispersion in Step 2 to obtain carboxylated vanadium diselenide nanosheet dispersion; Step 4: Preparation of composite material: Add polyvinylidene fluoride to the carboxylated vanadium diselenide nanosheet dispersion in step 3 to obtain the composite material.

[0015] Further, in step 1, the molar ratio of vanadium to selenium is 1:(1.8-2.2).

[0016] Furthermore, in step 1, the transport agent includes iodine.

[0017] Furthermore, in step 1, the sealing device includes a quartz tube.

[0018] Furthermore, in step 1, the heating device includes a tubular furnace.

[0019] Furthermore, in step 1, the heat treatment temperature is 800-900℃, and the time is 13-15 days.

[0020] Furthermore, in step 1, after the heat treatment, cooling, cleaning, and drying processes are performed sequentially.

[0021] Furthermore, in step 1, the drying process is carried out at a temperature of 50-80°C for 20-30 hours.

[0022] Furthermore, in step 2, the stripping process includes placing the vanadium diselenide crystal at the cathode of the electrolytic cell.

[0023] Furthermore, in step 2, the cathode potential is (-4) - (-6) V.

[0024] Further, in step 2, the electrolyte used for the stripping treatment includes a tetrabutylammonium propylene carbonate solution, a tetrapropylammonium N,N'-dimethylformamide solution, or a tetrapropylammonium dimethyl sulfoxide solution.

[0025] Furthermore, in step 2, the concentration of the electrolyte is 0.01-0.1 mol / L.

[0026] Furthermore, in step 2, the separation process includes centrifugation.

[0027] Furthermore, in step 2, the centrifugation speed is 10000-20000 r / min, and the time is 1-2 min.

[0028] Furthermore, in step 2, the washing treatment reagent includes N,N'-dimethylformamide or dimethyl sulfoxide.

[0029] Furthermore, in step 2, the washing process is performed at least three times.

[0030] Furthermore, in step 2, the concentration of the vanadium diselenide nanosheet dispersion is 4-6 mg / mL.

[0031] Furthermore, in step 2, after the washing process, ultrasonic treatment is performed.

[0032] Furthermore, in step 2, the ultrasonic treatment time is 5-15 minutes.

[0033] Further, in step 3, the carboxyl diazonium salt includes benzoic acid diazonium salt, o-nitrobenzoic acid diazonium salt, or p-hydroxybenzoic acid diazonium salt.

[0034] Furthermore, in step 3, the concentration of the carboxydiazonium salt solution is 8-12 mmol / L.

[0035] Furthermore, in step 3, the carboxyl diazonium salt is added to the vanadium diselenide nanosheet dispersion in step 2, and the mixture is stirred simultaneously.

[0036] Furthermore, in step 3, the stirring treatment is carried out at a temperature of 40-70°C for 10-15 hours.

[0037] Further, in step 4, polyvinylidene fluoride is added to the carboxylated vanadium diselenide nanosheet dispersion in step 3, and the mixture is stirred and then dried.

[0038] Furthermore, in step 4, the stirring treatment is carried out at a temperature of 50-70°C for a time of 30-60 minutes.

[0039] Furthermore, in step 4, the drying process is carried out at a temperature of 60-80°C for 20-24 hours.

[0040] Furthermore, in step 1, after the vanadium and selenium are mixed, a chemical reaction occurs after the heating treatment to generate vanadium diselenide. The role of the transport agent is to generate a volatile compound with the raw materials, which is then carried to the growth zone by the gas phase, inducing the vanadium diselenide crystal (vanadium diselenide has a typical layered transition metal chalcogenide structure, with covalent bonds within the layers and weak van der Waals forces between the layers) to grow in a directional manner, thereby improving the crystal purity and integrity.

[0041] Furthermore, in step 2, the vanadium diselenide crystal serves as the cathode of the electrolytic cell. The cations in the electrolyte are inserted into the interlayer of the vanadium diselenide crystal under the drive of the electric field. After the cations are inserted, the interlayer distance increases, the van der Waals force is further weakened, and the electric field generates stress, which promotes the separation of the crystal layers and forms a single layer or a few layers of vanadium diselenide nanosheets.

[0042] Furthermore, in step 3, the vanadium diselenide nanosheets are in a 1T metallic state with a high surface charge density. The diazo group in the carboxyl diazonium salt is a strong electrophile that can undergo an electrophilic reaction with the surface of the vanadium diselenide nanosheets, causing the carboxyl group to be covalently attached to the surface of the vanadium diselenide nanosheets to form a Se-C bond.

[0043] Furthermore, in step 4, the polyvinylidene fluoride is a high molecular polymer. The carboxyl groups on the surface of the carboxylated vanadium diselenide nanosheets and the fluorine atoms in the polyvinylidene fluoride molecules form hydrogen bonds or polar interactions, resulting in a strong interfacial bonding force between the two.

[0044] The present invention provides a magnetoelectric sensor, the sensor comprising the aforementioned composite material.

[0045] The present invention provides a wearable flexible device, the device including the magnetoelectric sensor.

[0046] Furthermore, the device includes a smartwatch, a wristband, or headphones.

[0047] Beneficial effects of the present invention In step 1, vanadium and selenium are heated in a sealed environment under the action of a transport agent to form vanadium diselenide crystals with a regular structure, providing the basic structural unit for the orderliness of the composite material. In step 2, the vanadium diselenide nanosheets obtained by peeling, separating and washing retain the ordered characteristics of the crystals and are evenly dispersed, becoming the key to the ordered arrangement inside the composite material. In step 3, the carboxylation modification enhances the compatibility between vanadium diselenide nanosheets and polyvinylidene fluoride (PVDF), which is conducive to the orderly combination of the two. In step 4, PVDF is oriented under the induction of carboxylated vanadium diselenide nanosheets, which significantly improves the orientation factor of the composite material and promotes the formation of more β phase of PVDF in the composite material.

[0048] The significantly increased orientation factor (order) and β-phase polyvinylidene fluoride (PVDF) content in the composite material significantly enhance its ferromagnetic, ferroelectric, and mechanical properties. Vanadium diselenide, a transition metal chalcogenide, possesses unpaired electrons and exhibits ferromagnetic properties. The ordered arrangement of nanosheets allows for the orderly superposition of magnetic moments along a specific direction, enhancing the total magnetic moment. Simultaneously, carboxylation at the interface reduces nanosheet aggregation, further improving the ferromagnetic properties of the composite material. β-phase PVDF itself exhibits strong polarity, which is further amplified by ordered arrangement, significantly improving the ferroelectric properties of the composite material. Ordered arrangement enables efficient stress transfer along the nanosheet plane (reducing stress concentration). The enhanced interfacial bonding (hydrogen bonding / polar interaction) through carboxylation ensures synergistic stress distribution between the nanosheets and the PVDF matrix (preventing interfacial delamination). Furthermore, the high strength of the two-dimensional nanosheets (intralayer covalent bonds) acts as a "reinforcing phase," further enhancing the mechanical strength of the composite material. Attached Figure Description

[0049] Figure 1 The XRD diffraction pattern of the composite material in Example 1; Figure 2 The infrared spectrum of the composite material in Example 1; Figure 3 This is a transmission electron microscope image of vanadium diselenide nanosheets in Example 1; Figure 4 An atomic force microscope image of the carboxylated vanadium diselenide nanosheets in Example 1; Figure 5 This is a high-resolution transmission electron microscope image of the composite material in Example 1. Detailed Implementation

[0050] Example 1 A polymer nanocomposite material S1 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium benzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.71, and the content of the β phase is 86% based on the total mass of polyvinylidene fluoride in the composite material.

[0051] The XRD diffraction pattern of the composite material is as follows Figure 1 As shown: the (020) characteristic diffraction peak of the α phase of polyvinylidene fluoride was observed at a 2θ angle of 18.6°, and the (110) characteristic diffraction peak of the β phase of polyvinylidene fluoride was observed at a 2θ angle of 20.6°.

[0052] The infrared spectrum of the composite material is as follows Figure 2 As shown: at wavenumbers of 763 and 876 cm⁻¹ -1Characteristic α-phase peaks of polyvinylidene fluoride were observed at wavenumbers of 840, 1071, 1168, 1273, and 1403 cm⁻¹. -1 The characteristic peak of the β phase of polyvinylidene fluoride was observed at [location].

[0053] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75%.

[0054] As shown in Table 1, the saturation magnetization of the composite material is 8.3 × 10⁻⁶ at 25℃. -3 The composite material has an emu / g, a Curie temperature of 156.9℃, and a fracture strength of 47.9MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0055] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 6.6 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 15 days. Then, cool, clean, and dry it in sequence at 60℃ for 20 hours to obtain vanadium diselenide crystals.

[0056] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -5V, the anode was a platinum wire, and the electrolyte was a 0.05 mol / L tetrabutylammonium carbonate solution. Then, the mixture was sequentially centrifuged, washed, and sonicated. The centrifugation speed was 10000 r / min for 1 min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 5 mg / mL. The sonication time was 10 min. The vanadium diselenide nanosheets are as follows... Figure 3 As shown.

[0057] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium benzoate to the vanadium diselenide nanosheet dispersion from Step 2 to a concentration of 12 mmol / L and stir. The stirring temperature is 45℃ for 12 h to obtain the carboxylated vanadium diselenide nanosheet dispersion. The carboxylated vanadium diselenide nanosheets are as follows... Figure 4 As shown.

[0058] Step 4: Preparation of the composite material: First, add 15 mg of polyvinylidene fluoride to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir at 50°C for 30 min. Then, drop the mixture onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60°C for 24 h to obtain the composite material. The composite material is shown below. Figure 5 As shown, the darker areas are carboxylated vanadium diselenide nanosheets (indicated by the white arrows), and the lighter areas are polyvinylidene fluoride. Overall, they are arranged in an orderly, alternating layered pattern of carboxylated vanadium diselenide nanosheets and polyvinylidene fluoride.

[0059] A magnetoelectric sensor comprising the aforementioned composite material.

[0060] A smartwatch that includes a magnetoelectric sensor.

[0061] Example 2 A polymer nanocomposite material S2 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium salt of o-nitrobenzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.7, and the content of the β phase is 83% based on the total mass of polyvinylidene fluoride in the composite material.

[0062] The XRD diffraction pattern and infrared spectrum of the composite material are respectively compared with... Figure 1 and Figure 2 Similarly, based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 80%.

[0063] As shown in Table 1, the saturation magnetization of the composite material is 3.4 × 10⁻⁶ at 25℃. -3 The composite material has an emu / g, a Curie temperature of 143.9℃, and a fracture strength of 36.5MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0064] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 6 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 15 days. Then, cool, clean, and dry the mixture sequentially at 80℃ for 20 hours to obtain vanadium diselenide crystals.

[0065] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -4V, the anode was a platinum wire, and the electrolyte was a 0.03mol / L tetrapropylammonium N,N'-dimethylformamide solution. Then, the mixture was centrifuged, washed, and sonicated sequentially. The centrifugation speed was 15000r / min for 2min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 5mg / mL. The sonication time was 15min.

[0066] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium salt of o-nitrobenzoic acid to the vanadium diselenide nanosheet dispersion in Step 2 to a concentration of 10 mmol / L and stir. The stirring temperature is 50℃ and the stirring time is 15 h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0067] Step 4: Preparation of composite material: First, take 20 mg of polyvinylidene fluoride and add it to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 70℃ and the time is 40 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 70℃ for 24 h to obtain the composite material.

[0068] A magnetoelectric sensor comprising the aforementioned composite material.

[0069] A wristband that includes a magnetoelectric sensor.

[0070] Example 3 A polymer nanocomposite material S3 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium salt of p-hydroxybenzoic acid and polyvinylidene fluoride. The orientation factor of the composite material is 0.67, and the content of the β phase is 80% based on the total mass of polyvinylidene fluoride in the composite material.

[0071] The XRD diffraction pattern and infrared spectrum of the composite material are respectively compared with... Figure 1 and Figure 2 Similarly, based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 85%.

[0072] As shown in Table 1, the saturation magnetization of the composite material is 0.8 × 10⁻⁶ at 25℃. -3 The composite material has an emu / g, a Curie temperature of 137.9℃, and a fracture strength of 20.2MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0073] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 5.8 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 900℃ for 15 days. Then, cool, clean, and dry the mixture sequentially at 60℃ for 30 hours to obtain vanadium diselenide crystals.

[0074] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -6V, the anode was a platinum wire, and the electrolyte was a 0.1 mol / L tetrapropylammonium dimethyl sulfoxide solution. Then, centrifugation, washing, and ultrasonic treatment were performed sequentially. The centrifugation speed was 15000 r / min for 1 min, the washing reagent was dimethyl sulfoxide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 4 mg / mL. The ultrasonic treatment time was 5 min.

[0075] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium salt of p-hydroxybenzoic acid to the vanadium diselenide nanosheet dispersion in Step 2 to a concentration of 12 mmol / L and stir. The stirring temperature is 70℃ and the stirring time is 15h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0076] Step 4: Preparation of composite material: Take 22.7 mg of polyvinylidene fluoride and add it to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 70℃ and the time is 60 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 80℃ for 20 h to obtain the composite material.

[0077] A magnetoelectric sensor comprising the aforementioned composite material.

[0078] An earphone that includes a magnetoelectric sensor.

[0079] Example 4 A polymer nanocomposite material S4 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium benzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.55, and the content of the β phase is 78% based on the total mass of polyvinylidene fluoride in the composite material.

[0080] The XRD diffraction pattern and infrared spectrum of the composite material are respectively compared with... Figure 1 and Figure 2Similarly, based on the dry weight of the composite material as a percentage, the polyvinylidene fluoride content is 90%.

[0081] As shown in Table 1, the saturation magnetization of the composite material is 0.4 × 10⁻⁶ at 25℃. -3 The composite material has an emu / g, a Curie temperature of 130.3℃, and a fracture strength of 16.4MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0082] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 5.4 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 13 days. Then, cool, clean, and dry the mixture sequentially at 50℃ for 20 hours to obtain vanadium diselenide crystals.

[0083] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -4V, the anode was a platinum wire, and the electrolyte was a 0.01mol / L tetrabutylammonium carbonate solution. Then, the mixture was centrifuged, washed, and sonicated sequentially. The centrifugation speed was 20000r / min for 1min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 6mg / mL. The sonication time was 10min.

[0084] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium benzoate to the vanadium diselenide nanosheet dispersion from Step 2 to a concentration of 8 mmol / L and stir. The stirring temperature is 50℃ and the stirring time is 10 h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0085] Step 4: Preparation of composite material: Take 54 mg of polyvinylidene fluoride and add it to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 50 °C and the time is 60 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60 °C for 24 h to obtain the composite material.

[0086] A magnetoelectric sensor comprising the aforementioned composite material.

[0087] A smartwatch that includes a magnetoelectric sensor.

[0088] Comparative Example 1 A polymer nanocomposite material D1 with magnetoelectric effect: The raw materials for the composite material include nickel nitrate hexahydrate, oxalic acid, ferric nitrate nonahydrate, and polyvinylidene fluoride. The orientation factor of the composite material is 0.2, and the content of the β phase is 46% based on the total mass of polyvinylidene fluoride in the composite material.

[0089] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75%.

[0090] As shown in Table 1, the saturation magnetization of the composite material at 25℃ is 0.05 × 10⁻⁶. -3 The composite material has an emu / g, a Curie temperature of 101.5℃, and a fracture strength of 3.5MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0091] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of nickel ferrite: First, dissolve nickel nitrate hexahydrate, oxalic acid, and ferric nitrate nonahydrate in water at a ratio of 1:2:4 and stir to obtain a mixed solution. Then, add sodium hydroxide to the mixed solution until the concentration is 10 mol / L and the pH value is 14. Then, transfer it to a polytetrafluoroethylene container for annealing at 130℃ for 24 hours. Finally, separate, wash, and dry the solution sequentially at 100℃ for 24 hours.

[0092] Step 2: Preparation of composite material: Dissolve the nickel ferrite from Step 1 in N,N'-dimethylformamide and sonicate for 1 hour to obtain a 15% nanoparticle solution. Then, add 450 mg of polyvinylidene fluoride to 1 mL of the nanoparticle solution and stir at 60°C for 3 hours. Then, drop the solution onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60°C for 24 hours to obtain the composite material.

[0093] A magnetoelectric sensor comprising the aforementioned composite material.

[0094] A smartwatch that includes a magnetoelectric sensor.

[0095] Comparative Example 2 A polymer nanocomposite material D2 with magnetoelectric effect: The raw materials for the composite material include cobalt ferrite and polyvinylidene fluoride. The orientation factor of the composite material is 0.31, and the content of the β phase is 41% based on the total mass of polyvinylidene fluoride in the composite material.

[0096] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75%.

[0097] As shown in Table 1, the saturation magnetization of the composite material at 25℃ is 0.08 × 10⁻⁶. -3 The composite material has an emu / g, a Curie temperature of 105.2℃, and a fracture strength of 4.5MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0098] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: First, polyvinylidene fluoride (PVDF) is dissolved in N,N'-dimethylformamide and stirred to obtain a mixed solution. The PVDF content is 8% based on the total mass of the mixed solution. The stirring temperature is 60℃ and the stirring time is 2 hours. Then, cobalt ferrite is added to the mixed solution, followed by high-speed stirring and low-speed degassing treatment. Finally, the mixture is dropped onto a glass substrate and dried in a vacuum drying oven at 50-80℃ to obtain the composite material.

[0099] A magnetoelectric sensor comprising the aforementioned composite material.

[0100] A smartwatch that includes a magnetoelectric sensor.

[0101] Comparative Example 3 A polymer nanocomposite material D3 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium benzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.25, and the content of the β phase is 45% based on the total mass of polyvinylidene fluoride in the composite material.

[0102] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 95%.

[0103] As shown in Table 1, the saturation magnetization of the composite material at 25℃ is 0.005 × 10⁻⁶. -3 The composite material has an emu / g, a Curie temperature of 111.6℃, and a fracture strength of 5.1MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0104] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 6.6 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 15 days. Then, cool, clean, and dry it in sequence at 60℃ for 20 hours to obtain vanadium diselenide crystals.

[0105] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -5V, the anode was a platinum wire, and the electrolyte was a 0.05mol / L tetrabutylammonium propylene carbonate solution. Then, centrifugation, washing, and ultrasonic treatment were performed sequentially. The centrifugation speed was 10000r / min for 1min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 5mg / mL. The ultrasonic treatment time was 10min.

[0106] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium benzoate to the vanadium diselenide nanosheet dispersion from Step 2 to a concentration of 12 mmol / L and stir. The stirring temperature is 45℃ and the stirring time is 12 h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0107] Step 4: Preparation of composite material: First, add 15 mg of polyvinylidene fluoride to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 50 °C and the stirring time is 30 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60 °C for 24 h to obtain the composite material.

[0108] A magnetoelectric sensor comprising the aforementioned composite material.

[0109] A smartwatch that includes a magnetoelectric sensor.

[0110] Comparative Example 4 A polymer nanocomposite material D4 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium benzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.27, and the content of the β phase is 48% based on the total mass of polyvinylidene fluoride in the composite material.

[0111] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 70%.

[0112] As shown in Table 1, the saturation magnetization of the composite material at 25℃ is 0.01 × 10⁻⁶. -3The composite material has an emu / g, a Curie temperature of 113.8℃, and a fracture strength of 8.4MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0113] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 6.6 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 15 days. Then, cool, clean, and dry it in sequence at 60℃ for 20 hours to obtain vanadium diselenide crystals.

[0114] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -5V, the anode was a platinum wire, and the electrolyte was a 0.05mol / L tetrabutylammonium propylene carbonate solution. Then, centrifugation, washing, and ultrasonic treatment were performed sequentially. The centrifugation speed was 10000r / min for 1min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 5mg / mL. The ultrasonic treatment time was 10min.

[0115] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium benzoate to the vanadium diselenide nanosheet dispersion from Step 2 to a concentration of 12 mmol / L and stir. The stirring temperature is 45℃ and the stirring time is 12 h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0116] Step 4: Preparation of composite material: First, add 15 mg of polyvinylidene fluoride to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 50 °C and the stirring time is 30 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60 °C for 24 h to obtain the composite material.

[0117] A magnetoelectric sensor comprising the aforementioned composite material.

[0118] A smartwatch that includes a magnetoelectric sensor.

[0119] Comparative Example 5 A polymer nanocomposite material D5 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium benzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.34, and the content of the β phase is 55% based on the total mass of polyvinylidene fluoride in the composite material.

[0120] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75%.

[0121] As shown in Table 1, the saturation magnetization of the composite material at 25℃ is 0.02 × 10⁻⁶. -3 The composite material has an emu / g, a Curie temperature of 115.9℃, and a fracture strength of 6.4MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0122] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 6.6 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 15 days. Then, cool, clean, and dry it in sequence at 60℃ for 20 hours to obtain vanadium diselenide crystals.

[0123] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -5V, the anode was a platinum wire, and the electrolyte was a 0.05mol / L tetrabutylammonium propylene carbonate solution. Then, centrifugation, washing, and ultrasonic treatment were performed sequentially. The centrifugation speed was 10000r / min for 1min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 3mg / mL. The ultrasonic treatment time was 10min.

[0124] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium benzoate to the vanadium diselenide nanosheet dispersion from Step 2 to a concentration of 12 mmol / L and stir. The stirring temperature is 45℃ and the stirring time is 12 h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0125] Step 4: Preparation of composite material: First, add 15 mg of polyvinylidene fluoride to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 50 °C and the stirring time is 30 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60 °C for 24 h to obtain the composite material.

[0126] A magnetoelectric sensor comprising the aforementioned composite material.

[0127] A smartwatch that includes a magnetoelectric sensor.

[0128] Comparative Example 6 A polymer nanocomposite material D6 with magnetoelectric effect: The raw materials for the composite material include vanadium, selenium, diazonium benzoate and polyvinylidene fluoride. The orientation factor of the composite material is 0.4, and the content of the β phase is 51% based on the total mass of polyvinylidene fluoride in the composite material.

[0129] Based on the dry weight of the composite material as a percentage, the content of polyvinylidene fluoride is 75%.

[0130] As shown in Table 1, the saturation magnetization of the composite material at 25℃ is 0.007 × 10⁻⁶. -3 The composite material has an emu / g, a Curie temperature of 107.5℃, and a fracture strength of 7.7MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

[0131] A method for preparing a polymer nanocomposite material with magnetoelectric effect, the method comprising the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix 3 mmol of vanadium and 6.6 mmol of selenium, then add iodine to obtain a mixture. First, seal the mixture in a quartz tube, then place the quartz tube in a tube furnace equipped with a thermocouple probe and heat it at 800℃ for 15 days. Then, cool, clean, and dry it in sequence at 60℃ for 20 hours to obtain vanadium diselenide crystals.

[0132] Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals from Step 1 were placed on the cathode of an electrolytic cell for exfoliation. The cathode potential was -5V, the anode was a platinum wire, and the electrolyte was a 0.05mol / L tetrabutylammonium carbonate solution. Then, the mixture was centrifuged, washed, and sonicated sequentially. The centrifugation speed was 10000r / min for 1min, the washing reagent was N,N'-dimethylformamide, and the washing was performed 3 times to obtain a vanadium diselenide nanosheet dispersion with a concentration of 7mg / mL. The sonication time was 10min.

[0133] Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add diazonium benzoate to the vanadium diselenide nanosheet dispersion from Step 2 to a concentration of 12 mmol / L and stir. The stirring temperature is 45℃ and the stirring time is 12 h to obtain the carboxylated vanadium diselenide nanosheet dispersion.

[0134] Step 4: Preparation of composite material: First, add 15 mg of polyvinylidene fluoride to 1 mL of the carboxylated vanadium diselenide nanosheet dispersion from Step 3 and stir. The stirring temperature is 50 °C and the stirring time is 30 min. Then, drop it onto the surface of a plasma-treated hydrophilic glass slide and dry it at 60 °C for 24 h to obtain the composite material.

[0135] A magnetoelectric sensor comprising the aforementioned composite material.

[0136] A smartwatch that includes a magnetoelectric sensor.

[0137] Table 1. Comparison of saturation magnetization, Curie temperature, and fracture strength of the composite materials in Examples 1-4 and Comparative Examples 1-6.

[0138] In summary, Comparative Examples 1-2 involve combining polyvinylidene fluoride (PVDF) with ferromagnetic nanofillers from existing technologies to prepare composite materials with magnetoelectric effects. The internal structure of these composite materials is disordered (the orientation factor is significantly lower than that of Examples 1-4), and the PVDF content in the β phase is also significantly lower. In Comparative Examples 3-4, based on the dry weight of the composite materials, the PVDF content is 95% and 70%, respectively, which is outside the numerical range of Examples 1-4 of this invention. In Comparative Examples 5-6, the concentrations of the vanadium diselenide nanosheet dispersions are 3 mg / mL and 7 mg / mL, respectively, which are also outside the numerical range of Examples 1-4 of this invention. The saturation magnetization, Curie temperature, and fracture strength of the composite materials D1-D6 prepared in this way are significantly lower than those of Examples 1-4 (S1-S4). This invention prepares a specific composite material through a specific method, and this specific composite material has better ferromagnetic properties, ferroelectric properties, and mechanical strength compared to existing technologies.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A polymer nanocomposite material exhibiting magnetoelectric effect, characterized in that, The raw materials of the composite material include vanadium, selenium, carboxylated diazonium salt and polyvinylidene fluoride, wherein the orientation factor of the composite material is 0.55-0.71, and the content of β phase is 78-86% based on the total mass of polyvinylidene fluoride in the composite material.

2. The composite material according to claim 1, characterized in that, In the XRD diffraction pattern of the composite material: the (020) characteristic diffraction peak of the α phase of the polyvinylidene fluoride was observed at a 2θ angle of 18.6±0.2°, and the (110) characteristic diffraction peak of the β phase of the polyvinylidene fluoride was observed at a 2θ angle of 20.6±0.2°.

3. The composite material according to claim 1, characterized in that, In the infrared spectrum of the composite material: at wavenumbers of 763±3 and 876±3 cm⁻¹ -1 The α-phase characteristic peaks of the polyvinylidene fluoride were observed at wavenumbers of 840±3, 1071±3, 1168±3, 1273±3, and 1403±3 cm⁻¹. -1 The β-phase characteristic peak of the polyvinylidene fluoride was observed at [location].

4. The composite material according to claim 1, characterized in that, Based on the dry weight of the composite material, the content of polyvinylidene fluoride is 75-90%.

5. The composite material according to claim 1, characterized in that, At 25℃, the saturation magnetization of the composite material is 0.4-8.3×10⁻⁶. -3 The composite material has an emu / g content, a Curie temperature of 130.3-156.9℃, and a fracture strength of 16.4-47.9MPa. The saturation magnetization is used to characterize the ferromagnetic properties of the composite material, the Curie temperature is used to characterize the ferroelectric properties, and the fracture strength is used to characterize the mechanical strength.

6. A method for preparing the composite material according to any one of claims 1-5, characterized in that, The method includes the following steps: Step 1: Preparation of vanadium diselenide crystals: Mix vanadium and selenium, then add a transport agent to obtain a mixture. Seal and heat the mixture sequentially to obtain vanadium diselenide crystals. Step 2: Preparation of vanadium diselenide nanosheet dispersion: First, the vanadium diselenide crystals in Step 1 are stripped, and then separated and washed sequentially to obtain vanadium diselenide nanosheet dispersion; Step 3: Preparation of carboxylated vanadium diselenide nanosheet dispersion: Add carboxyl diazonium salt to the vanadium diselenide nanosheet dispersion in Step 2 to obtain carboxylated vanadium diselenide nanosheet dispersion; Step 4: Preparation of composite material: Add polyvinylidene fluoride to the carboxylated vanadium diselenide nanosheet dispersion in step 3 to obtain the composite material.

7. The method according to claim 6, characterized in that, In step 2, the stripping process includes placing the vanadium diselenide crystal at the cathode of the electrolytic cell.

8. The method according to claim 6, characterized in that, In step 2, the washing reagent includes N,N'-dimethylformamide or dimethyl sulfoxide.

9. The method according to claim 6, characterized in that, In step 3, the carboxyl diazonium salt includes benzoic acid diazonium salt, o-nitrobenzoic acid diazonium salt, or p-hydroxybenzoic acid diazonium salt.

10. A magnetoelectric sensor, characterized in that, The magnetoelectric sensor comprises the composite material according to any one of claims 1-5.

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